Real world efficacy of maribavir when used as pre-emptive therapy for cytomegalovirus reactivation in alloHCT patients who are intolerant, refractory or resistant

Background: Cytomegalovirus (CMV) infection impacts morbidity and mortality in allogeneic cell transplant (allo-HCT) recipients. Pre-emptive therapy (PET) is a strategy where antivirals are initiated once plasma CMV viral load reaches a defined threshold. Existing antivirals (val)ganciclovir and foscarnet have significant toxicities (myelosuppression and renal dysfunction) and often necessitate inpatient admissions. Maribavir (MBV) is a newer antiviral with minimal toxicity and demonstrated efficacy in refractory/resistant (R/R) CMV infection and patients intolerant of other antivirals. We evaluated the efficacy and safety of MBV as PET of CMV as first- or second-line therapy in allo-HCT recipients who are intolerant, R/R to other antivirals.
Methods: A retrospective, multicentre cohort study evaluating patients who received MBV from November 2023 to November 2025. MBV was administered until 2 consecutive undetectable viral loads defining CMV clearance. Data was extracted from electronic medical records and collected using electronic case report forms.
Results: A total of 20 patients with 32 MBV treatment episodes were included. 71.8% of treatment episodes met the primary endpoint of CMV clearance. The most common indications for MBV were intolerance to (val)ganciclovir due to bone marrow dysfunction (59.3%) and the avoidance of a hospital admission for foscarnet administration (65.6%). The median number of inpatient hospital days saved was 24.5 per treatment episode (IQR12.8-29.0); 53.1% of treatment episodes were managed in the outpatient setting alone. MBV was changed to an alternate antiviral in 10 episodes including confirmed MBV-resistance in two patients (mutations T409M and H411Y). MBV-attributed adverse effects not resulting in discontinuation were reported in 3 patients. All-cause mortality was reported in 20.0% of patients with 1 CMV disease related death.

Conclusion: This real-world study demonstrates that MBV is an effective, well-tolerated antiviral when used as PET. It is beneficial in cases of bone marrow dysfunction and reduces inpatient hospitalisation days in patients who require foscarnet.